I've come across this a few times. Don't know how helpful it is for everyone, I thinks its a neat little tutorial if anyone is planning on painting which I imagine you all are. http://www.androidblues.com/cloudtut.html

I took a screen grab of the above post from Google art project and moved it more into the colour palette thats been specified just to see all the colours that we get. Its not accurate obviously but it shows nicely how to avoid the colourised look. See the pinks through, the greens, and purples in the bottom image? Well as you can see they are all relatively blue! No greens here. Similarly in the top image, see that nice patch of pinky-blue sky in the middle - so do I but my colour picker doesn't.

Dust and Cloud study. I plan on doing a few more studies between now and the end. Trying to avoid jumping straight in without loosening up first. Thinking about volume, shape and scale. Today I received this in the post too:

I'm a right cloud geek now, I now know that those cool anvil clouds are called Incus. As the cumulonimbus swells upwards forming a cumulo congestus. Its vapor starts to form ice crystals which spread in every direction. Usually this happens at the tropopause (base of the stratosphere)! Geek.